Underground pipes can break and crack with ground movement over time. Where a pipe breaks, ground water enters the pipe. If the pipe is a sewer this ground water will mix with the sewage and ultimately be treated at the water treatment works. This is uneconomic. The fluid carried by a damaged pipe may also leak into the ground surrounding the pipe and polluting the ground water.
It is undesirable to completely replace damaged pipes as this requires significant excavation, which is difficult when pipes underlie man-made structures such as roads and buildings.
It is therefore desirable to repair or restore the pipes while they are in situ. This can be achieved by lining the pipe.
Lining a main sewer has been achieved by coating the interior of the main pipe with a fabric lining impregnated with resin and then curing the resin. Contact is made between the fabric and the wall of the main pipe by either directly inflating a ‘sock’ of fabric impregnated with resin or by inflating a balloon that supports a tube of fabric impregnated with resin. The resin cures and the fabric lining forms a hard liner. A robotic cutter is then used to cut holes in the main liner where lateral pipes join the main pipe.
This is, however, only a partial solution. Damage to the laterals themselves may significantly contribute to ingress to or egress from the sewer system.
The laterals are generally accessible only from one clean-out (man-hole). The laterals are lined by shooting a lining into the lateral either from the man hole or from inside the main sewer. The shooting process uses a sock-like balloon attached to a vessel at its opening. The balloon is turned inside-out (inverted) and extends into the interior of the vessel in its primed state. When inflated by fluid provided to the vessel the sock-like balloon extends from the vessel and presses a tubular lining against the wall of the lateral pipe. The tubular lining is made of fabric impregnated with resin, which cures to form a liner. The balloon can then be deflated and removed.
This procedure creates an area at the junction between a lined main pipe and a lined lateral pipe which may be unsealed or poorly sealed.
It is therefore desirable to tie the lining of the main pipe and the lining of the lateral pipe together.
One way of trying to achieve this to insert a resin fabric tube from the main and shoot (invert) the tube 10-30 m up the lateral pipe. The tube terminates on the main with a flared end like a flange or top-hat bonded to the main sewer lining. The claimed benefit of this procedure is that in a single process the lateral pipe and the junction between the main and lateral are lined. However, this process is not always effective.
It is an object of the present invention to provide an afternative mechanism for lining a junction.